| Boiling and Kit methods were used to extract genomic DNA from six different leaching bacteria. The extracting effects of the two methods were compared in terms of the concentration, purity and recovery of the extracted genomic DNA and the influence of extracted genomic DNA on PCR. The levels of sensitivity of the two methods were compared through Real-time PCR where the same mesophilic acidophile was treated with different decimal amounts of cells. The results showed that the genomic DNA extracted from gram positive bacteria (1strain), gram negative bacteria (4strains), and archaea (1strain) respectively with the same amount of bacteria (108cells) of by the two methods differed to large extent. The six groups of genomic DNA extracted through the boiling method are much purer than those extracted through Kit method with OD26o/OD28o values of the former near the range of1.8to2.0(the OD26o/OD28o value of pure DNA falls between1.8to2.0). Recovery of genomic DNA through the former method can be up to16.7times that of the latter. While compared to the kit method, the concentration of extracted DNA template could be detected by Real-time PCR with a smaller number of cells (102cells) when DNA was extracted by the boiling method, in which aspect the sensitivity of boiling method is higher than that of kit method.In the study, three groups of experiment were carried out. In the first experiment,0.1g and0.32g S0were added respectively; in the second,0.2g,1.0g and1.8g FeSO4·7H2O were added respectively; while in the third,0.32g S0and0.2g FeSO4·7H2O were added simultaneously. pH values, iron-oxidizing activity and sulfur-oxidizing activity of the bacteria and leaching rate of the three experiments were compared. The results show that the oxidizing activity of bacteria and the leaching rate of ore are different with the addition of different energy materials. In the third experiment where0.1g elemental sulfur and0.2g ferrous sulfate were added simultaneously, the copper leaching rate is the highest among the three experiments, with a value of66.1%. In the first and second experiments, the leaching is inhibited.The chalcopyrite was leached from mixed culture of A. ferrooxidans and A. thiooxidans. Two leaching systems were involved in this part. In the first leaching system,50mg/L ethyl xanthate and100mg/L butylamine aerofloat were added to the mixed culture, while in the other leaching system, nothing was added. The leaching rates of two systems were compared; the adsorption differences of A. ferrooxidans and A. thiooxidans onto chalcopyrite with and without flotation reagents were studied respectively; the surface group change of chalcopyrite with and without reagents was analyzed; and a comparative analysis of the leached residues of the two systems were conducted. The results show that the maximum adsorption of A. ferrooxidans could be achieved on chalcopyrite with reagents, up to4.37x1010cells/g,20times that of A. ferrooxidans on chalcopyrite without reagents, while the maximum adsorption of A. thiooxidans on chalcopyrite with or without reagents are almost the same, which is probably due to the reason that the mediated action of flotation reagents is different for different bacteria, although it increases the bacterial adsorption sites on the surface of concentration. On the other hand, in the leaching system of chalcopyrite with reagents, a lot of jarosite was found in the precipitation at the later stage due to the large amount of Fe3+generated by the high iron-oxidizing activity of bacteria in leaching process. On the27th day, due to the action of flotation reagents, the copper leaching rate of chalcopyrite with reagents is97.1%, while that of chalcopyrite without reagents is only58%. |
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